The present invention concerns tools with a combined abrasive and fragmentation action for the production of profiles or cuts in sheets of fragile material such as marble, granite, stone, glass and the like.
The production of contour edges on sheets or plates of relatively fragile material such as marble, stone, granite, glass or the like, that is to say an operation involving pre-cutting to measure with a contour which is straight or curved in various ways, involves producing the edge in such a way as to afford a configuration in varying shapes The shape may for example be a semicircumference, or a quarter of a circumference or another profile, with curves and possibly with portions of an undercut configuration. Such production procedure requires the removal of material in substantial amounts.
That kind of production procedure was hitherto effected by using rotary diamond tools of a profile corresponding in reverse relationship to that which was to be copied on the edge of the sheet of material being produced. In the prior art those tools are made of metal to which diamonds are applied using known procedures, and the tools were rotated at high speed against the edge of the sheet being produced, in order to remove the excess material by an abrasive action until the contour of the desired shape was achieved.
In practice all the excess material was removed by abrasion, leaving at the end a contour which was shaped in accordance with the configuration of the tool. Subsequently, a finishing and polishing operation is effected by means of other diamond-bearing tools of the same configuration.
The known operating procedure involved in the removal of material along the edge of a sheet of marble or the like suffers from the disadvantage that all the excess material has to be removed by abrasion using the diamond-bearing tool, involving a considerable amount of time and entailing excessive wear of the tool which, once consumed, has to be scrapped since, unlike the milling cutters used for machining metals, they cannot be subjected to a re-sharpening procedure.
A tool of that kind is illustrated for example in EP-B-0 478 518 which has a sensor element which rolls against the surface of the edge of the sheet of material being machined so as to maintain a constant cutting drive into the edge of the sheet of material to follow its contour both in a straight line and in a curve.
It is the object of the present invention to provide a tool, for processing fragile materials of the above-indicated type, combining an abrasive action produced by the diamond means with a mechanical action involving breaking the material which is not removed by the diamond-bearing part, taking advantage of the fragility properties of the material being processed, and thereby permitting a higher processing speed with the same amount of material being removed and a lower tool cost by virtue of the smaller amount of diamond used in the construction of the tool.
Accordingly the tool of the present invention is defined by claim 1.